A positive photosensitive resin composition, includes: (A) a resin containing an acid-dissociable group having a specific acetal structure as defined in the specification, which is alkali-insoluble or sparingly alkali-soluble and becomes alkali-soluble when the acid-dissociable group is dissociated; (B) a compound capable of generating an acid upon irradiation with actinic rays or radiation; (C) a crosslinking agent; and (D) an adhesion aid, and a cured film forming method uses the same.